The disclosed embodiments relate to a linkage between at least one support element and an aircraft fuselage. A support element means a supporting surface such as the airfoil or a horizontal fin of the aircraft. More precisely, the disclosed embodiments relate to a device for fastening such a support element to the fuselage structure of the aircraft.
In flight, the aircraft is subjected to various aerodynamic stresses that have repercussions on both the airfoil and on the fuselage and the linkage between these two elements. For example, the airfoil tends to bend in flight under the vertical force, which compresses the flanks of the fuselage. In the same way, compressive and tensile forces are applied to the airfoil, involving an elongation of the bottom surface and a shortening of the top surface of said airfoil, imposing a similar deformation on the central airfoil casing contained in the bottom section of the fuselage. The linkage between the airfoil and the aircraft fuselage must also support the stresses due to the excursion of the airfoil, to the forces arising from the bending torque of the airfoil, from the aerodynamic load, and from shear stresses on the airfoil. In the same way, the linkage between the airfoil and the fuselage must support the deformations due to the pressure and compression of the lateral walls of the fuselage deforming the entire fuselage volume.
Various fastening devices are presently known for linking the airfoil to the fuselage, considering the mechanical and manufacturing constraints of an aircraft.
For example, in the case of an airfoil positioned in the lower part of the central section of the fuselage, it is known how to use a cross and T-junction. To do this, the fuselage integrates the central airfoil casing in its internal volume, and then each half-airfoil is brought laterally to the right or left wall of the central airfoil casing and is fastened there. The horizontal cross enables the linkage of the top surface panels of the central casing and of the airfoil while the horizontal T enables the linkage of the bottom surface panels of the central casing and of the airfoil. The fuselage is linked to the central airfoil casing by the horizontal cross and by the frames. Such a fastening device greatly complicates the manufacture of the fuselage, especially in its central part. Actually, it is necessary to adapt the fuselage structure so that said fuselage is compatible with the displacements between the fuselage and the airfoil during certain maneuvers. Furthermore, the fastening of the half-airfoils is very complex and calls upon numerous fasteners to join all of the upper/lower surface panels to one another.
It is also known how to fasten the airfoil in the upper part of the fuselage through a “cap” joint. Such an airfoil is made in one part to be brought to the upper part of the fuselage, once each is finished. The weight of such an assembly is not optimal for two principal reasons; the introduction of load is localized, and the number of parts is great. In other respects, such a device is difficult to apply without a weight penalty for an aircraft that has a low-flex wing, for which there is a concentration of forces on the rear longeron of the airfoil, in some cases of flight determining the size of the structure.
It is also known how to use tension bolt junctions. However, such junctions are unsatisfactory since they do not permit optimal transmission of airfoil torsional forces to the fuselage.